A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section.
Pneumatic systems of the aircraft utilize engine bleed air for pneumatic power. The engine bleed air is obtained from locations within the compressor section to provide air at pressures required by the pneumatic system. Pressures within the compressor section vary during engine operating cycle. At lower engine power settings pressures within the compressor section may closely match demand of the pneumatic systems, however at higher engine power settings pressures at the same compressor location may greatly exceed demand. For this reason, engine bleed air is typically obtained from different locations within the compressor section depending on the current engine operating conditions in an effort to improve engine efficiency. Even tapping air from many different locations, variation of air pressures during engine operation can create difficulties in matching the demand of the pneumatic system. Differences between airflow and pressure demands of the pneumatic system and available air pressures from the engine can reduce engine operating efficiency.